Method for fabricating a sensor semiconductor device with sensor chip

ABSTRACT

A sensor semiconductor device and a method for fabricating the same are proposed. A sensor chip is mounted on a substrate, and a dielectric layer and a circuit layer are formed on the substrate, wherein the circuit layer is electrically connected to the substrate and the sensor chip. The dielectric layer is formed with an opening for exposing a sensor region of the sensor chip. A light-penetrable lid covers the opening of the dielectric layer, such that light is able to penetrate the light-penetrable lid to reach the sensor region and activate the sensor chip. The sensor chip can be electrically connected to an external device via a plurality of solder balls implanted on a surface of the substrate not for mounting the sensor chip. Therefore, the sensor semiconductor device is fabricated in a cost-effective manner, and circuit cracking and a know good die (KGD) problem are prevented.

FIELD OF THE INVENTION

The present invention relates to sensor semiconductor devices andmethods for fabricating the same, and more particularly, to a chip-scalepackaged (CSP) sensor semiconductor device, and a method for fabricatingthe sensor semiconductor device.

BACKGROUND OF THE INVENTION

In a conventional image sensor package, a sensor chip is mounted on achip carrier and is electrically connected to the chip carrier viabonding wires, and a piece of glass is provided above the sensor chip toallow an image to be captured by the sensor chip. The image sensorpackage can be integrated to an external device such as a printedcircuit board (PCB) to be used in various electronic products such asdigital still camera (DSC), digital video camera (DVC), optical mouse,cellular phone, fingerprint scanner, and so on.

Along with expansion of data transmission capacity and development ofminiaturized and portable electronic products, integrated circuit (IC)packages have been developed to have an advanced chip-scale packaged(CSP) structure in response to the requirements such as plentyinput/output (I/O) connections, high heat dissipating efficiency andsize miniaturization for integrated circuits. Therefore, a chip-scalepackaged sensor semiconductor device is provided to effectively reduce asize of the conventional image sensor package, wherein the semiconductordevice is merely slightly larger in size than a sensor chip incorporatedtherein and thus can be effectively applied to miniaturized electronicproducts.

FIG. 1 (PRIOR ART) shows a chip-scale packaged sensor semiconductordevice disclosed by U.S. Pat. No. 6,646,289. As shown in FIG. 1 (PRIORART), during fabrication of a wafer comprising sensor chips 11, a pieceof glass 12 is applied over an active surface of the wafer to protectsensor regions 18 of the sensor chips 11, and an epoxy layer 13 and aprotective layer 14 are applied over a non-active surface of the wafer.An etching process is performed on the non-active surface of the waferto form a plurality of inclined slots 15, such that electrode pads 110of the sensor chips 11 are exposed, and patterned circuit layers 16 areformed on side walls of the inclined slots 15 and extended to a bottomsurface of the protective layer 14, allowing the circuit layers 16 to beelectrically connected to the electrode pads 110 of the sensor chips 11.A plurality of solder balls 17 can subsequently be implanted on thecircuit layers 16 at the bottom surface of the protective layer 14, anda singulation process is performed to form individual chip-scalepackaged sensor semiconductor devices, such that the sensorsemiconductor devices can directly be electrically connected to anexternal device by the solder balls 17.

However, in the foregoing sensor semiconductor device, since the circuitlayers formed on the side walls of the inclined slots have an acuteangle relative to the electrode pads of the sensor chip electricallyconnected to the circuit layers, such acute-angle connection positionsbetween the circuit layers and the electrode pads may easily be subjectto stress concentration, thereby causing problems such as circuitcracking, failure in electrical connection, and so on. As fabrication ofthe foregoing sensor semiconductor device is directly performed on thewafer, which requires complicated fabrication processes and does noteffectively solve a known good die (KGD) problem, making the fabricationcosts greatly increased.

Therefore, the problem to be solved herein is to provide a chip-scalesensor semiconductor device and a method for fabricating the same,whereby the sensor semiconductor device can be cost-effectivelyfabricated and a circuit-cracking problem is avoided.

SUMMARY OF THE INVENTION

In light of the above drawbacks in the conventional technology, anobjective of the present invention is to provide a sensor semiconductordevice and a method for fabricating the same, whereby the sensorsemiconductor device can be easily fabricated.

Another objective of the present invention is to provide acost-effective sensor semiconductor device and a method for fabricatingthe same.

Still another objective of the present invention is to provide a sensorsemiconductor device and a method for fabricating the same, whereby acircuit-cracking problem is avoided.

A further objective of the present invention is to provide a chip-scalesensor semiconductor device and a method for fabricating the same.

In accordance with the foregoing and other objectives, the presentinvention proposes a method for fabricating a sensor semiconductordevice, comprising the steps of: mounting at least one sensor chip on asubstrate having a plurality of connecting pads, wherein an activesurface of the sensor chip is formed with a sensor region and aplurality of electrode pads, and a non-active surface of the sensor chipis attached to the substrate; applying a dielectric layer on thesubstrate and the sensor chip, wherein the dielectric layer is formedwith a plurality of first openings corresponding in position to theconnecting pads of the substrate and the electrode pads of the sensorchip; forming a circuit layer on the dielectric layer, wherein thecircuit layer is electrically connected to the connecting pads of thesubstrate and the electrode pads of the sensor chip; forming a secondopening in the dielectric layer at a position corresponding to thesensor region of the sensor chip; and providing a light-penetrable lidto cover the second opening of the dielectric layer corresponding to thesensor region of the sensor chip, and implanting a plurality of solderballs on a surface of the substrate not for mounting the sensor chip. Ifthe fabrication method is performed in a batch-type manner, asingulation process is further required to form a plurality ofindividual sensor semiconductor devices.

The present invention also proposes a sensor semiconductor device,comprising: a substrate having a first surface and a correspondingsecond surface, wherein the first surface of the substrate is formedwith a plurality of connecting pads; a sensor chip mounted on the firstsurface of the substrate, wherein an active surface of the sensor chipis formed with a sensor region and a plurality of electrode pads, and anon-active surface of the sensor chip is attached to the substrate; adielectric layer applied on the substrate and the sensor chip, whereinthe dielectric layer is formed with a plurality of first openingscorresponding in position to the connecting pads of the substrate andthe electrode pads of the sensor chip and a second opening correspondingin position to the sensor region of the sensor chip; a circuit layerformed on the dielectric layer, and electrically connected to theconnecting pads of the substrate and the electrode pads of the sensorchip; a light-penetrable lid mounted on the circuit layer, for coveringthe second opening of the dielectric layer corresponding to the sensorregion of the sensor chip; and a plurality of solder balls implanted onthe second surface of the substrate.

By the sensor semiconductor device and the method for fabricating thesame in the present invention, a sensor chip is firstly mounted on asubstrate, and then a dielectric layer and a circuit layer are formed onthe substrate by a build-up process. The circuit layer is electricallyconnected to the substrate and the sensor chip, such that the sensorchip can be electrically connected to the substrate via the circuitlayer. The dielectric layer is formed with an opening for exposing asensor region of the sensor chip. A light-penetrable lid is provided tocover the opening of the dielectric layer, such that light is able topenetrate the light-penetrable lid to reach the sensor region andactivate the sensor chip. A plurality of solder balls are implanted on asurface of the substrate not for mounting the sensor chip, so as toallow the sensor chip to be electrically connected to an external deviceby the solder balls. In the present invention, the sensor chip can besubjected to a test and any defective chip failing in the test iseliminated in advance, such that the reliability of subsequentfabricating processes is improved and a known good die (KGD) problem isavoided. The sensor chip can be thinned before being mounted on thesubstrate, such that an overall thickness of the fabricatedsemiconductor device is reduced. A chamfer can be formed on the activesurface of the sensor chip by bevel cutting so as to reduce a stressconcentration effect. By the arrangement that the sensor chip iselectrically connected to the substrate via the circuit layer throughthe build-up process, and the sensor chip is electrically connected tothe solder balls via circuits and conductive vias of the substrate andis further electrically connected to the external device via the solderballs, the sensor semiconductor device can be fabricated in an easy andcost-effective manner as compared to the conventional technology, and achip-cracking problem is prevented in the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more fully understood by reading thefollowing detailed description of the preferred embodiments, withreference made to the accompanying drawings, wherein:

FIG. 1 (PRIOR ART) is a cross-sectional view of a chip-scale packagedsensor semiconductor device as disclosed in U.S. Pat. No. 6,646,289;

FIGS. 2A to 2E are cross-sectional views of steps of a method forfabricating a sensor semiconductor device according to a first preferredembodiment of the present invention;

FIG. 3 is a cross-sectional view of a sensor semiconductor deviceaccording to a second preferred embodiment of the present invention; and

FIG. 4 is a cross-sectional view of a sensor semiconductor deviceaccording to a third preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of a sensor semiconductor device and a method forfabricating the same proposed in the present invention are describedbelow with reference to FIGS. 2A-2E, 3 and 4. It should be noted thatthe drawings are simplified schematic diagrams for illustrating thebasic design of the present invention and thus only show relevantelements to the present invention. The drawings are not made with theactual amount, shape and size of the elements. In practice, the number,shape and size of the elements can be flexibly modified, and an elementlayout may be more complex.

FIGS. 2A to 2E are cross-sectional views of steps of a method forfabricating a sensor semiconductor device according to a first preferredembodiment of the present invention. In this embodiment, a batch-typemethod is employed to fabricate the sensor semiconductor device. Itshould be understood that the sensor semiconductor device in the presentinvention can also be fabricated in a singular-type manner undersuitable fabrication conditions.

Referring to FIG. 2A, a substrate module plate 20 comprising a pluralityof substrates 200 is provided. The substrate module plate 20 can be amatrix-type or strip-type substrate module plate. A plurality ofconnecting pads 21 are formed on each of the substrates 200. At leastone sensor chip 22 is mounted on each of the substrates 200. The sensorchip 22 has an active surface 221 and a corresponding non-active surface222, wherein the active surface 221 of the sensor chip 22 is formed witha sensor region 223 and a plurality of electrode pads 224, and thenon-active surface 222 of the sensor chip 22 is attached to each of thesubstrates 200. A thinning process can be performed on the non-activesurface 222 of the sensor chip 22 in advance, and good dies are selectedas the sensor chips 22 to be mounted on the substrates 200.

Referring to FIG. 2B, a dielectric layer 23 is formed on the substratemodule plate 20 to cover the substrates 200 and the sensor chips 22. Thedielectric layer 23 is formed with a plurality of openings 230corresponding in position to the connecting pads 21 of the substrates200 and the electrode pads 224 of the sensor chips 22.

Referring to FIG. 2C, a circuit layer 24 is formed on the dielectriclayer 23 and is electrically connected to the connecting pads 21 of thesubstrates 200 and the electrode pads 224 of the sensor chips 22.

Referring to FIG. 2D, openings 231 are further formed in the dielectriclayer 23 at positions corresponding to the sensor regions 223 of thesensor chips 22 on the substrates 200, such that the sensor regions 223of the sensor chips 22 are exposed.

Referring to FIG. 2E, a light-penetrable lid 25 is provided to cover theopenings 231 of the dielectric layers 23, and a plurality of solderballs 26 are implanted on a surface of each of the substrates 200 notfor mounting the sensor chip 22. A singulation process is performed toform a plurality of sensor semiconductor devices. The light-penetrablelid 25 can be made of glass or transparent paste. Therefore, the sensorchip can be electrically connected to an external device via theelectrode pads, the circuit layer, the connecting pads of the substrate,internal conductive structures of the substrate, and the solder balls.

By the foregoing fabrication method, the present invention also providesa sensor semiconductor device, comprising: a substrate 200 having afirst surface and a corresponding second surface, wherein the firstsurface of the substrate 200 is formed with a plurality of connectingpads 21; a sensor chip 22 mounted on the first surface of the substrate200, wherein an active surface 221 of the sensor chip 22 is formed witha sensor region 223 and a plurality of electrode pads 224, and anon-active surface 222 of the sensor chip 22 is attached to thesubstrate 200; a dielectric layer 23 applied on the substrate 200 andthe sensor chip 22, wherein the dielectric layer 23 is formed with aplurality of openings 230 corresponding in position to the connectingpads 21 of the substrate 200 and the electrode pads 224 of the sensorchip 22 and an opening 231 corresponding in position to the sensorregion 223 of the sensor chip 22; a circuit layer 24 formed on thedielectric layer 23, and electrically connected to the connecting pads21 of the substrate 200 and the electrode pads 224 of the sensor chip22; and a light-penetrable lid 25 mounted on the circuit layer 24, forcovering the opening 231 of the dielectric layer 23. The sensorsemiconductor device further comprises a plurality of solder balls 26implanted on the second surface of the substrate 200.

By the sensor semiconductor device and the method for fabricating thesame in the present invention, a sensor chip is firstly mounted on asubstrate, and then a dielectric layer and a circuit layer are formed onthe substrate by a build-up process. The circuit layer is electricallyconnected to the substrate and the sensor chip, such that the sensorchip can be electrically connected to the substrate via the circuitlayer. The dielectric layer is formed with an opening for exposing asensor region of the sensor chip. A light-penetrable lid is provided tocover the opening of the dielectric layer, such that light is able topenetrate the light-penetrable lid to reach the sensor region andactivate the sensor chip. A plurality of solder balls are implanted on asurface of the substrate not for mounting the sensor chip, so as toallow the sensor chip to be electrically connected to an external deviceby the solder balls. In the present invention, the sensor chip can besubjected to a test and any defective chip failing in the test iseliminated in advance, such that the reliability of subsequentfabricating processes is improved and a known good die (KGD) problem isavoided. By the arrangement that the sensor chip is electricallyconnected to the substrate via the circuit layer through the build-upprocess, and is further electrically connected to the external devicevia the solder balls, the sensor semiconductor device can be fabricatedin an easy and cost-effective manner as compared to the conventionaltechnology, and a chip-cracking problem is prevented in the presentinvention.

FIG. 3 is a cross-sectional view of a sensor semiconductor deviceaccording to a second preferred embodiment of the present invention.

The sensor semiconductor device of the second embodiment is fabricatedby a method similar to that used in the first embodiment, with a primarydifference in that as shown in FIG. 3, a bevel cutting process isperformed on the sensor chip 22 in advance to form a chamfer 221 a on aperipheral area of the active surface 221 of the sensor chip 22, suchthat a stress concentration effect on the peripheral area of the activesurface 221 of the sensor chip 22 is further reduced when subsequentlyforming the dielectric layer 23 and the circuit layer 24.

FIG. 4 is a cross-sectional view of a sensor semiconductor deviceaccording to a third preferred embodiment of the present invention.

The sensor semiconductor device of the third embodiment is fabricated bya method similar to that used in the first embodiment, with a primarydifference in that as shown in FIG. 4, a circuit build-up process isperformed on the circuit layer 24 that is electrically connected to theconnecting pads 21 of the substrate 200 and the electrode pads 224 ofthe sensor chip 22. Firstly, a dielectric layer 33 is formed on thecircuit layer 24, wherein the dielectric layer 33 is formed withopenings to partly expose the circuit layer 24. Then, a circuit layer 34is formed on the dielectric layer 33 and is electrically connected tothe circuit layer 24 underneath the dielectric layer 33. The sensorregion 223 of the sensor chip 22 is exposed from the dielectric layers23, 33, such that light is able to penetrate the light-penetrable lid 25to reach the sensor region 223. Therefore, electrical performances ofthe sensor semiconductor device can be improved by the circuit build-upstructure. It should be noted that the number of build-up circuit layersis not limited to that shown in the drawing and can be increasedaccording to practical requirements of electrical design.

The invention has been described using exemplary preferred embodiments.However, it is to be understood that the scope of the invention is notlimited to the disclosed embodiments. On the contrary, it is intended tocover various modifications and similar arrangements. For example, themanner of electrical connection between sensor chip and substrate andthe provision of passive component and/or heat dissipating structure canbe flexibly modified and arranged. The scope of the claims, therefore,should be accorded the broadest interpretation so as to encompass allsuch modifications and similar arrangements.

1. A method for fabricating a sensor semiconductor device, comprisingthe steps of: mounting at least one sensor chip on at least onesubstrate having a first surface and a corresponding second surface, thesensor chip having an active surface and a corresponding non-activesurface, wherein the first surface of the substrate is formed with aplurality of connecting pads, the active surface of the sensor chip isformed with a sensor region and a plurality of electrode pads, and thenon-active surface of the sensor chip is attached to the first surfaceof the substrate; applying a dielectric layer on the substrate and thesensor chip, wherein the dielectric layer is formed with a plurality offirst openings corresponding in position to the connecting pads of thesubstrate and the electrode pads of the sensor chip; forming a circuitlayer on the dielectric layer, wherein the circuit layer is electricallyconnected to the connecting pads of the substrate and the electrode padsof the sensor chip; forming a second opening in the dielectric layer ata position corresponding to the sensor region of the sensor chip; andproviding a light-penetrable lid to cover the second opening of thedielectric layer corresponding to the sensor region of the sensor chip.2. The method of claim 1, further comprising a step of implanting aplurality of solder balls on the second surface of the substrate.
 3. Themethod of claim 1, further comprising a step of performing a circuitbuild-up process on the circuit layer that is electrically connected tothe connecting pads of the substrate and the electrode pads of thesensor chip.
 4. The method of claim 1, wherein a chamfer is formed on aperipheral area of the active surface of the sensor chip.
 5. The methodof claim 1, wherein the sensor chip is thinned before being mounted onthe substrate.
 6. The method of claim 1, wherein a good die is selectedas the sensor chip before mounting the sensor chip on the substrate. 7.The method of claim 1, wherein the at least one substrate comprises atleast one single substrate, a matrix of substrates, or a strip ofsubstrates.
 8. The method of claim 1, wherein the sensor semiconductordevice is a chip-scale packaged sensor semiconductor device.